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Paula Span “During the past four weeks, have you been tired? Been exhausted? Had difficulty getting motivated to do anything at all?” These questions — which a substantial chunk of the population probably could answer in the affirmative — appeared on a questionnaire used in a major European study published recently in The New England Journal of Medicine. The authors were researching the effectiveness of a drug that is widely, if controversially, used to treat older adults with subclinical hypothyroidism, better known as a slightly underactive thyroid. So many Americans take that medication — levothyroxine (brand name Synthroid) — that it topped the list of prescription drugs dispensed in the United States in 2015, according to the research firm QuintilesIMS Institute. With 121 million prescriptions annually, levothyroxine outpaced statins, blood pressure meds — and everything else. A Johns Hopkins survey published last year found that more than 15 percent of older Americans were taking it. So you’d think these study results would come as shocking news: The European team reported that in older people with mild hypothyroidism, the drug had no significant effect on symptoms. At all. Instead, the results bolstered what a number of geriatricians and endocrinologists have suspected for years. “It’s a strong signal that this is an overused medication,” said Dr. Juan Brito, an endocrinologist at the Mayo Clinic. “Some people really need this medicine, but not the vast majority of people who are taking it.” © 2017 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23522 - Posted: 04.22.2017

By RONI CARYN RABIN Television ads for “low T” have sparked a rise in the use of testosterone gels, patches and injections by older men in recent years, according to a new report. But anyone hoping that a dose of testosterone will provide an easy antidote for sagging muscles, flagging energy and a retiring sex drive may find the results of recent government studies of the sex hormone sobering. The latest clinical trials, published over the past year, are the first rigorous ones to assess the potential beneficial effects of testosterone treatment for older men with abnormally low levels of the hormone. Scientists followed 790 men age 65 and older who had blood testosterone levels below 275 nanograms per deciliter of blood, well below the average for healthy young men and lower than would be expected with normal aging. The men also had symptoms reflecting their low hormone levels, like loss of sex drive. Half the participants were treated with testosterone gel, and half were given a placebo gel. The studies reported mixed results, finding that over the yearlong study period, testosterone therapy corrected anemia, or low levels of red blood cells, which can cause fatigue, and increased bone density. But a study to see if testosterone improved memory or cognitive function found no effects. Meanwhile, a red flag warning of possible risks to the heart emerged from the studies: Imaging tests found a greater buildup of noncalcified plaque in the coronary arteries of men treated with testosterone for a year, an indicator of cardiac risk, compared with those who were given a placebo gel. The findings of plaque were not a complete surprise; many reports have tied testosterone use to an increase in heart attacks, and the Food and Drug Administration already requires testosterone products to carry warnings of an increased risk of heart attacks and stroke (men at high risk of cardiovascular disease were not allowed to participate in the latest trials). But observational studies, which are weaker, have yielded mixed results over all, with one study published last month finding that men taking testosterone actually had fewer heart problems. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 23413 - Posted: 03.28.2017

Patricia Neighmond Many men over 65 with low testosterone levels say their sense of well-being, not to mention sexual function, isn't what it used to be. That's why some doctors prescribe testosterone replacement. But the effectiveness of testosterone has been controversial. Studies of the risks and benefits have been mixed, and the Food and Drug Administration beefed up its warnings about cardiac side effects of testosterone supplementation in 2015. And the findings of five studies released Tuesday aren't likely to clear up the confusion. They appear in JAMA, the journal of the American Medical Association and JAMA Internal Medicine. The studies are collectively called the Testosterone Trials (TTrials) and they compared a testosterone gel, AndroGel, against a placebo. The results are based on 788 men with below normal levels of testosterone studied at 12 sites across the country over a year. Overall, researchers saw improvements in bone density and bone strength in men who used a testosterone gel, which raised their testosterone to levels seen in younger men. In men with unexplained anemia, testosterone also improved iron levels in the blood. (A reviewer of the study raised questions about whether it was done ethically.) But in men using testosterone who had been reporting memory problems at the start of the study, there were no improvements in memory or cognition. And there were worrisome signs of an increase in the risk of cardiovascular problems. © 2017 npr

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 23267 - Posted: 02.22.2017

By LISA SANDERS, M.D. “You don’t look well,” the man at the gas station told the older woman in the car. He’d known her for years, always thinking of her as a lively, robust woman. But that day she looked pale and tired. Her sharp blue eyes seemed dim. She gave a feeble smile. “I don’t feel well at all,” she told him. There’s an urgent-care clinic just up the street, he said. Could she make it there? She was nearly 45 minutes away from her home in Halifax, Nova Scotia. Stopping just up the street seemed a much better option. At the clinic, the doctor took one look at her, put a blood pressure cuff around her arm and told her assistant to call an ambulance. The rest of the day was a blur. The woman remembers being bundled onto a stretcher and one of the E.M.T.s saying her blood pressure was very low. It was an odd thing to hear, because her blood pressure was usually high enough to require three medications. She was taken to the emergency room at the Queen Elizabeth II Health Sciences Center in Halifax. She remembers being fussed over — having blood drawn, receiving intravenous fluids, feeling sticky snaps being placed on her chest that connected her to a continuous heart monitor. She had been a nurse for many years when she was younger, yet seeing herself at the center of these familiar activities was strange. A blood test indicated that there may have been damage to her heart. The doctor told her she was having a heart attack, she recalls. You’ve got the wrong patient, she thought to herself. Sure, she had a little high blood pressure, a little asthma, a little back pain. But problems with her heart? Never. The patient used a cane, but she had no difficulty getting up on the exam table — an important test of mobility. © 2017 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 23101 - Posted: 01.14.2017

By Virginia Morell Only three known species go through menopause: killer whales, short-finned pilot whales, and humans. Two years ago, scientists suggested whales do this to focus their attention on the survival of their families rather than on birthing more offspring. But now this same team reports there’s another—and darker—reason: Older females enter menopause because their eldest daughters begin having calves, leading to fights over resources. The findings might also apply to humans, the scientists say. “What an interesting paper,” says Phyllis Lee, a behavioral ecologist at the University of Stirling in the United Kingdom, who was not involved in the study. “It brings two perspectives on menopause neatly together, and provides an elegant model for its rarity.” The new work came about when Darren Croft, a behavioral ecologist at the University of Exeter in the United Kingdom, and his colleagues looked back on their 2015 killer whale menopause study. “That showed how they helped and why they lived so long after menopause, but it didn’t explain why they stop reproducing,” he says, noting that in other species, such as elephants, older females also share wisdom and knowledge with their daughters, but continue to have calves. © 2017 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 23096 - Posted: 01.13.2017

National Institutes of Health (NIH) researchers have discovered molecular mechanisms that may underlie a woman’s susceptibility to disabling irritability, sadness, and anxiety in the days leading up to her menstrual period. Such premenstrual dysphoric disorder (PMDD) affects 2 to 5 percent of women of reproductive age, whereas less severe premenstrual syndrome (PMS) is much more common. “We found dysregulated expression in a suspect gene complex which adds to evidence that PMDD is a disorder of cellular response to estrogen and progesterone,” explained Peter Schmidt, M.D. of the NIH’s National Institute of Mental Health, Behavioral Endocrinology Branch. “Learning more about the role of this gene complex holds hope for improved treatment of such prevalent reproductive endocrine-related mood disorders.” Schmidt, David Goldman, M.D., of the NIH’s National Institute on Alcohol Abuse and Alcoholism, and colleagues, report on their findings January 3, 2017 in the journal Molecular Psychiatry. “This is a big moment for women’s health, because it establishes that women with PMDD have an intrinsic difference in their molecular apparatus for response to sex hormones – not just emotional behaviors they should be able to voluntarily control,” said Goldman. By the late 1990s, the NIMH team had demonstrated (link is external) that women who regularly experience mood disorder symptoms just prior to their periods were abnormally sensitive to normal changes in sex hormones — even though their hormone levels were normal. But the cause remained a mystery.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 23052 - Posted: 01.04.2017

By LISA SANDERS, M.D. On Thursday, we challenged Well readers to take on the complicated case of a 50-year-old woman who felt feverish and couldn’t stop vomiting and who ended up losing a lot of weight. Like the doctors who saw her as she searched for a diagnosis, many of you focused on her recent journey to Kenya as the source of her symptoms. It was a completely reasonable approach, and one that was extensively explored by the doctors who cared for her. But ultimately it was incorrect. This was a really tough case. Indeed, only three of you got it right. The correct diagnosis was: Hyperthyroidism Thyroid hormone controls metabolism. The more of this hormone flowing in the body, the harder the body works. Because this hormone plays such an important role in how we function, the body tightly regulates how much of it is released and when. But just like every other system in the body, that regulatory mechanism can mess up, releasing either too little hormone (hypothyroidism) or, as in this case, too much. The usual symptoms of hyperthyroidism are pretty apparent: The heart races; patients are sweaty, shaky, itchy and sometimes feverish. The appetite increases, but because the entire body is revved up, there is often weight loss. Bowel movements become more frequent and sleep harder to come by. Frequent and uncontrolled vomiting is less common but has been reported. This patient had all of these symptoms. The most common cause of hyperthyroidism is an autoimmune disorder known as Graves’ disease, named after Dr. Robert Graves, a 19th-century Irish physician who wrote about the phenomenon of rapid and violent palpitations associated with an enlarged thyroid gland. In the 20th century it was discovered that the symptoms result when antibodies, the foot soldiers of the immune system, cause excess stimulation of the thyroid gland, resulting in the uncontrolled production and release of thyroid hormone. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 22624 - Posted: 09.03.2016

By Knvul Sheikh Although millions of women use hormone therapy, those who try it in hopes of maintaining sharp memory and preventing the fuzzy thinking sometimes associated with menopause may be disappointed. A new study indicates that taking estrogen does not significantly affect verbal memory and other mental skills. “There is no change in cognitive abilities associated with estrogen therapy for postmenopausal women, regardless of their age,” says Victor Henderson, a neurologist at Stanford University and the study’s lead author. Evidence of positive and negative effects of such hormone therapy has ping-ponged over the years, with some observational studies in postmenopausal women and research in animal models, suggesting it improves cognitive function and memory. But other previous research, including a long-term National Institutes of Health Women’s Health Initiative memory study published in 2004, has suggested that taking estrogen increases the risk of cognitive impairment and dementia in women over 65 years old. Henderson says one explanation for these contradictory findings may be that after menopause begins there is a “critical period” in which hormone therapy could still benefit relatively young women—if they start early enough. So in their study, which appears in the July 20 online Neurology, Henderson and his team recruited 567 healthy women, between ages 41 and 84, to examine how estrogen affected one group whose members were within six years of their last menstrual period and another whose members had started menopause at least 10 years earlier. © 2016 Scientific American

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 22470 - Posted: 07.23.2016

By Jessica Hamzelou TEENAGE pregnancies have hit record lows in the Western world, largely thanks to increased use of contraceptives of all kinds. But strangely, we don’t really know what hormonal contraceptives – pills, patches and injections that contain synthetic sex hormones – are doing to the developing bodies and brains of teenage girls. You’d be forgiven for assuming that we do. After all, the pill has been around for more than 50 years. It has been through many large trials assessing its effectiveness and safety, as have the more recent patches and rings, and the longer-lasting implants and injections. But those studies were done in adult women – very few have been in teenage girls. And biologically, there is a big difference. At puberty, our bodies undergo an upheaval as our hormones go haywire. It isn’t until our 20s that things settle down and our brains and bones reach maturity. “If a drug is going to be given to 11 and 12-year-olds, it needs to be tested in 11 and 12-year-olds,” says Joe Brierley of the clinical ethics committee at Great Ormond Street Hospital in London. Legislation introduced in the US in 2003 and in Europe in 2007 was intended to make this happen but a New Scientist investigation can reveal that there is still scant data on what contraceptives actually do to developing girls. The few studies that have been done suggest that tipping the balance of oestrogen and progesterone during this time may have far-reaching effects, although there is not yet enough data to say whether we should be alarmed. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 22407 - Posted: 07.08.2016

By Simon Oxenham The “cuddle chemical”. The “moral molecule”. Oxytocin has quite a reputation – but much of what we thought about the so-called “love hormone” may be wrong. Oxytocin is made by the hypothalamus and acts on the brain, playing a role in bonding, sex and pregnancy. But findings that a sniff of the hormone is enough to make people trust each other more are being called into question after a string of studies failed to replicate classic experiments. Paul Zak at the Centre for Neuroeconomic Studies in Claremont, California, made his moral molecule hypothesis famous in 2011 when he memorably squirted a syringe of the hormone into the air while delivering a TED talk. When people sniff oxytocin before playing a money-lending game, it increases how much they trust each other, he explained. But several teams have been unable to replicate his finding. Last November, Gideon Nave at the California Institute of Technology in Pasadena and his colleagues reviewed studies of oxytocin, and concluded that the effect of nasal squirts of the hormone on trust are not reliably different from zero. Nave’s team aren’t the only ones calling the moral molecule hypothesis into question. In 2012, Moïra Mikolajczak at the Catholic University of Louvain (UCL) in Belgium and her colleagues published their own seminal findings backing a link between trust and oxytocin. They found that when people filled out an anonymous questionnaire about their sex lives and fantasies, they were less likely to seal the envelopes they returned them in if given a nasal dose of oxytocin beforehand. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 22223 - Posted: 05.17.2016

Laura Glynn, Pregnancy brain typically refers to lapses in attention and memory. About 80 percent of new mothers report difficulties remembering things that once came naturally, and although not all studies support this, the weight of the evidence shows that during pregnancy, women exhibit measurable declines in important cognitive skills. But it's not all bad news. The maternal brain also features important enhancements. Mother rats score higher in tests of attention, foraging and planning than peers who have never given birth. These gains most likely render them better able to defend and provide for their pups. The benefits for human moms are less clear, but data are emerging that suggest human pregnancies initiate neural restructuring. A 2010 study found that in the first few months after giving birth, human females show changes in several key brain regions. Specifically, they often exhibit increased volume in the hypothalamus, striatum and amygdala—areas essential for emotional regulation and parental motivation—as well as in regions governing decision making and protective instincts. We can glean further evidence from behavioral changes during pregnancy. Many women exhibit blunted physiological and psychological responses to stress, which may afford mother and fetus protection from the potentially adverse effects of taxing situations. And in the postpartum period, the hormones that sustain breast-feeding maintain these dampened stress responses. © 2016 Scientific American

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 22208 - Posted: 05.12.2016

By Lisa Sanders, M.D. On Thursday we challenged Well readers to take on the case of a 59-year-old woman who had not been able to stop gaining weight. I presented the case as it was presented to the doctor who made the diagnosis and asked for the final piece of data provided by the patient as well as the correct cause of her symptoms. I thought the tough part of this case was something that few of my readers would have to contend with – that her complaints and past medical history were quite ordinary. Like many of us, she was overweight and she came to the doctor because she had difficulty losing weight. In the background she also had high blood pressure, obstructive sleep apnea and low back pain, knee pain and leg swelling. These are some of the most common reasons patients seek medical attention. Although her problems were run of the mill, the cause was not. And many of you had no difficulty spotting this zebra. The correct diagnosis was… Acromegaly The last piece of data, provided by the patient, was a photograph taken several years before. It was only by seeing the changes in the patient’s face that had occurred over the past few years that the doctor recognized that this patient’s problem was unusual. The first person to make this diagnosis was Dr. Clare O’Connor, a physician in the second year of her training in internal medicine. She plans to subspecialize in endocrinology. She says it was the swollen legs that didn’t compress that gave her the first clue. Well done. Acromegaly is a rare disease caused by an excess of growth hormone, usually due to a tumor in the pituitary gland of the brain. The disease’s name, from the Greek, serves as a fitting description of the most obvious symptoms: great (mega) extremity (akron). The tumor secretes a protein called growth hormone that signals the liver to produce a substance called insulin-like growth factor 1, or IGF 1, which in turn tells cells throughout the body to start proliferating. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 22097 - Posted: 04.12.2016

by Giuseppe Gangarossa When we think about sex hormones, notably estrogens and androgens, we usually associate them with sex, gender and body development. Like all hormones, they are chemical messengers, substances produced in one part of the body that go on to tell other parts what to do. However, we often have the tendency to forget the enormous impact that these steroid hormones have on brain functions. From animal studies, it has become clear that during early development, exposure of the brain to testosterone and estradiol, hormones present in both males and females, leads to irreversible changes in the nervous system (McCarthy et al., 2012). A growing and very appealing body of science suggests that sex hormones play a neuromodulatory role in cognitive brain function (Janowsky, 2006). Moreover, testosterone dysfunctions (hypogonadism, chemical castration, etc.) have shown to be associated with memory defects. However, in spite of these advances, it still remains an enigma how sex hormones affect the brain. In an interesting paper published in PLOS ONE, Picot and colleagues tried to fill in one piece of the puzzle. They investigated the neurobiological effects of cerebral androgen receptor (AR) ablation on hippocampal plasticity and cognitive performance in male rodents (Picot et al., 2016). Although several reports have already highlighted a link between sex hormones and cognitive function (Galea et al., 2008; Janowsky, 2006), much more needs to be done to fully elucidate the “non-sexual” functions of androgens.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 21930 - Posted: 02.25.2016

By GINA KOLATA More than a million men have smeared testosterone gels on their bodies in recent years, hoping it would rejuvenate them, energize them, and increase their libido. But until now, there has never been a rigorous study asking if there were any real benefits to testosterone therapy for healthy men with so-called low T. The first results of such research were published Wednesday in The New England Journal of Medicine. Although it found at best modest benefits, mostly in sexual functioning, it is a landmark study, said Dr. Eric S. Orwoll, a professor of medicine at Oregon Health and Science University, because it provides the first credible data on testosterone’s effects on some of the problems it is thought to resolve. Some doctors said they hoped the modest results might bring some sanity to the testosterone frenzy of recent years. “Frankly,” said Dr. Sundeep Khosla, a dean at the Mayo Clinic College of Medicine, “there is a lot of abuse.” Men lured by advertisements seek the drug, and Dr. Khosla said he had heard of doctors who prescribed it without first measuring the man’s testosterone levels to see if they were low. “What I hope is that this will bring a more conservative approach,” Dr. Orwoll said. “There is a lot of prescribing out there, and it doesn’t look like, for the average man, it will have a big effect.” The study, led by the Perelman School of Medicine at the University of Pennsylvania and funded by the National Institutes of Health and AbbVie, the maker of the testosterone gel AndroGel, involved 790 men 65 and older with low testosterone levels for their age. Testosterone levels normally fall as men age, but these men had levels on the low end — below 275 nanograms per deciliter of blood. Some of the men said they had lost their sexual drive, others said they were walking much slower than they used to, and others said they just felt blah, as if they had lost their zest for life. The men were randomly assigned to use AndroGel or a placebo for a year. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 21908 - Posted: 02.18.2016

By Darryl Fears Flushed down toilets, poured down sinks and excreted in urine, a chemical component in the pill wafts into sewage systems and ends up in various waterways where it collects in fairly heavy doses. That's where fish soak it up. A recent survey by the U.S. Geological Survey found that fish exposed to a synthetic hormone called 17a-ethinylestradiol, or EE2, produced offspring that struggled to fertilize eggs. The grandchildren of the originally exposed fish suffered a 30 percent decrease in their fertilization rate. The authors mulled the impact of what they discovered and decided it wasn't good. "If those trends continued, the potential for declines in overall population numbers might be expected in future generations," said Ramji Bhandari, a University of Missouri assistant research professor and a visiting scientist at USGS. "These adverse outcomes, if shown in natural populations, could have negative impacts on fish inhabiting contaminated aquatic environments." The study, with Bhandari as lead author, also determined that the chemical BPA, used widely in plastics, had a similar effect on the small Japanese medaka fish used for the research. The medaka was chosen because it reproduces quickly so that scientists can see results of subsequent generations faster than slow reproducing species such as smallmouth bass.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 21760 - Posted: 01.08.2016

By Puneet Kollipara The list of health problems that scientists can confidently link to exposure to hormone-disrupting chemicals has grown to include diabetes, cardiovascular disease, and obesity, a new scientific statement suggests. The statement, released today by the Endocrine Society, also adds support to the somewhat controversial idea that even minute doses of these chemicals can interfere with the activity of natural hormones, which play a major role in regulating physiology and behavior. But the report—which updates a similar statement released in 2009—is drawing sharp criticism from the chemical industry. An executive summary of the new statement, which synthesizes 1300 studies on endocrine disrupters, posits that scientists are more confident than ever before in linking these substances to a host of known health issues, including reproductive and developmental problems, thyroid impairment, certain reproductive cancers, and neurodevelopmental problems such as decreased IQ. But studies suggest those links can now be extended to heart and weight problems, and diabetes, says the executive summary's first author, Andrea C. Gore, a professor of pharmacology and toxicology at the University of Texas, Austin. Six years ago, scientists couldn’t make such a strong case for those links, Gore says, because there weren’t enough good studies. “But this has really been an emerging field where there is much stronger evidence now,” Gore told reporters today on a conference call. Still, some toxicologists and industry groups have long disputed the assertion that endocrine disrupters can trigger effects at minimal doses; this idea can be tough to test in lab animals, which are usually exposed to high doses in toxicology studies. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 21454 - Posted: 09.29.2015

By Sarah Schwartz Researchers have developed a chemical that transforms into a powerful hormone once inside a rat — but only in the brain, not the body. A protein in rats’ brains turns a chemical nicknamed DHED into the hormone estrogen, scientists report July 22 in Science Translational Medicine. This targeted treatment could provide estrogen to the brain and avoid potentially dangerous side effects in the body, the researchers say. “This is an interesting breakthrough,” says neuroendocrinologist Bruce McEwen of the Rockefeller University in New York City. The idea of treatments that affect the brain but not the body, or the body but not the brain, could be useful in treating a number of conditions, including cancer, he says. But the implications of this study for hormone replacement therapy in women is up for debate, a number of researchers say. In menopausal women or those who have had their ovaries surgically removed, lack of estrogen in the brain can cause symptoms such as hot flashes and sleep disturbances. Taking estrogen can relieve those symptoms but can cause side effects in the rest of the body, including an increased risk of certain cancers. The chemical DHED is nearly identical to natural human estrogen, but it has an extra oxygen atom. A specialized protein found in rodents’ brains recognizes the chemical and chops off the oxygen, turning DHED into estrogen. The body’s other organs lack this protein, so they can’t turn DHED into estrogen, says study author Laszlo Prokai, a chemical biologist at the University of North Texas Health Science Center in Fort Worth. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 21210 - Posted: 07.23.2015

Helen Shen In April 2011, Robert Froemke and his team were reprogramming the brains of virgin mice with a single hormone injection. Before the treatment, the female mice were largely indifferent to the cries of a distressed baby, and were even known to trample over them. But after an injection of oxytocin, the mice started to respond more like mothers, picking up the mewling pup in their mouths. Froemke, a neuroscientist at New York University's Langone Medical Center in New York City, was monitoring the animals' brains to find out why that happened. At first, the mice showed an irregular smattering of neural impulses when they heard the baby's cries. Then, as the oxytocin kicked in, the signal evolved into a more orderly pattern typical of a maternal brain. The study showed in unusual detail how the hormone changed the behaviour of neurons1. “Oxytocin is helping to transform the brain, to make it respond to those pup calls,” Froemke says. Oxytocin has been of keen interest to neuroscientists since the 1970s, when studies started to show that it could drive maternal behaviour and social attachment in various species. Its involvement in a range of social behaviours2, including monogamy in voles, mother–infant bonding in sheep, and even trust between humans, has earned it a reputation as the 'hug hormone'. “People just concluded it was a bonding molecule, a cuddling hormone, and that's the pervasive view in the popular press,” says Larry Young, a neuroscientist at Emory University in Atlanta, Georgia, who has been studying the molecule since the 1990s. “What we need to start thinking about is the more fundamental role that oxytocin has in the brain.” © 2015 Nature Publishing Group,

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 21095 - Posted: 06.25.2015

Steve Connor Having children can permanently affect the brain of women because the surge in female sex hormones during pregnancy can influence the development of key parts of the central nervous system, a series of studies has shown. The findings suggest that childbirth can affect the female brain, but they could also shed light on the controversy over whether hormone replacement therapy in menopausal women affects the risk of developing Alzheimer’s disease in later life, scientists said. The research looked at two of the oestrogen hormones used to treat the symptoms of menopausal women and found that they could have a complex effect depending on the age of the women and whether or not they had previously given birth. Although the work was mostly carried out on laboratory rats, the scientists said that the findings are more widely applicable to humans because the same hormones and brain cells are involved. The scientists found that the surge in oestrogen hormones during pregnancy, where levels can soar to several hundred times normal levels, can alter “neuroplasticity” or the re-growth of nerve cells in a part of the brain called the hippocampus, which is responsible for aspects of memory and spatial awareness. “Our most recent research show that previous motherhood alters cognition and neuroplasticity in response to hormone therapy, demonstrating that motherhood permanently alters the brain,” said Liisa Galea of the University of British Columbia in Vancouver, Canada.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 20982 - Posted: 05.26.2015

|By Julie Hecht Unlike porcupines, dogs are a relatively hands-on (actually, paws-on) species, both with one another and with us. YouTube has numerous videos of dogs essentially saying, “Just keep petting me, please. Yes, that’s it…more.” But this relationship is not one-sided. Many studies find that positive interactions between people and dogs can be beneficial for both species. Increases in β-endorphin (beta-endorphin), oxytocin and dopamine—neurochemicals associated with positive feelings and bonding—have been observed in both dogs and people after enjoyable interactions like petting, play and talking. Essentially, interacting with a dog, particularly a known dog, can have some of the same psychophysiological markers as when two emotionally attached people spend time together. But do certain types of interactions have an outsized impact? Dogs are incredibly attentive to human faces and, in some cases, even specific facial expressions. This seemingly routine, benign behavior—your dog turning to gaze on your beautiful face as you do his or hers—could actually hold a very important piece of the puzzle in our relationship with dogs, suggests a study published this week in Science. The new study, by Miho Nagasawa of Azabu University in Japan and colleagues, builds on Nagasawa’s previous work, published in Hormones and Behavior in 2009, that found owners and dogs sharing a long mutual gaze had higher levels of oxytocin in their urine than owners of dogs giving a shorter gaze. (Oxytocin, a humble peptide of nine amino acids that is sometimes called the “cuddle hormone,” has been implicated in social bonding and is instrumental to the cascade of hormonal changes leading up to and following birth.) Nagasawa and her colleagues concluded that their finding was “a manifestation of attachment behavior.” © 2015 Scientific American

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20816 - Posted: 04.18.2015